1

si"

1.0 M Methanol 20 psig Oxygen 2"x 2* Cell she

Figure 3. Relative methanol permeability and crossover rates observed with Nafion and newly developed membranes.

Stacks and Systems:

Five-cell stacks have been demonstrated at the 20 and 100 W level by JPL and Giner Inc., respectively with an aim to study stack designs and obtain parametric data on reactant flows and product management in order to be able to achieve a system concept demonstration at the end of December 1996. Performance data on five-cell stacks and membrane-electrode assemblies developed at JPL are presented in Figure 4.

CURRENT DENSITY, mA/cm2 Figure 4. Performance of 5-ceIl JPL-built direct methanol fuel cell stack at ambient pressure

This data shows the scalability of single cell technology to multi-cell stacks. The development of a 22-cell 60 W stack is presently being pursued for portable power applications. System sizing and thermal management studies are currently underway at JPL and Giner Inc., and power densities in the range of 1 OOWAkg appear attainable for complete systems.

Life testing of fuel cells:

Operation of a five-cell stack over periods extending over 2400 hours has been carried out at Giner Inc. The performance does not show any significant decline over this period. Continuous operation at high power densities for 200 hours at 90°C also indicate no significant concern relating to short-term degradation.

Acknowledgment:

The work presented here was carried out with support from DARPA and ARO, under a contract with the National Aeronautics and Space Agency at the Jet Propulsion Laboratory, California Institute of Technology.

References:

1. S. R Narayanan, T. Valdez, W. Chun, B. Nakamura, H. Frank and G. Halpert, Power Sources Conference 1996, Cherry Hill NJ.

2. S.Surampudi, S. R. Narayanan, E. Vamos, H. Frank and G.Halpert, J. Power Sources, 47(1994) 377-385.

3. J. Kosek, C.C. Cropley, A. B. La Conti, G. Wilson, S. R. Narayanan, E. Vamos, S. Surampudi and H. Frank, Proceedings of the IECEC 1993, Volume 1, p. 1209.

4. S. R Narayanan, A. Kindler, B. Jeffries-Nakamura, W. Chun, H. Frank, M.Smart, S. Surampudi and G.Halpert, Proceedings of the First International Symposium on Proton Conducting Fuel Cells I, p261,The Electrochemical Society, 1995 ( Eds. S. Gottesfeld, G. Halpert and A. Landgrebe)

5. S. R. Narayanan, A. Kindler, B. Jeffries-Nakamura, W. Chun, H. Frank, M.Smart, T. I. Valdez , S. Surampudi, J. Kosek and C. Cropley, " Recent Advances in PEM Liquid Feed Direct Methanol Fuel Cells," Proceedings of the Eleventh Annual Battery Conference on Applications an Advances, Long Beach, CA, January 1996.

PC25™ PRODUCT AND MANUFACTURING EXPERIENCE

Eugene W. Hall, William C. Riley and Gregory J, Sandelli International Fuel Cells Corporation South Windsor, Connecticut 06074

Product and manufacturing experience accumulated since the beginning of PC25 A production in 1991 provides a strong base of demonstration and experience for establishing future improvements to the PC25 power plant

Field Experience

The PC25 power plant operating fleet now totals 67 power plants of the A, B and C models and additional units are being installed. As shown in Figure 1, total operating time for the fleet exceeds 1.1 million hours and individual units are now passing 30,000 hours total operating time with 27 units having operated for over 20,000 hours. This experience with fuel cell stacks or power plants including laboratory testing and extensive field testing of prior phosphoric acid power plants. Consequently it provides the first meaningful opportunity to assess the durability and reliability of any fuel cell technology in actual service conditions although it is most directly applicable to the phosphoric acid fuel cell.

0 0

Post a comment